Weld underbeads in aluminum are usually large and frequently extend below the lower material surface a distance equal to three or more times the material thickness. On girth welds in some flow critical tubular weldments, the typically large underbeads tend to create a fluid flow restriction. Consequently, the underbead will require the utilization of some form of underbead support tooling or mechanical removal of the excessive weld reinforcement. Mechanical weld reinforcement removal is a slow, costly, manual operation and is frequently difficult or impossible due to the inaccessability of the weld underbead area produced by bends in the tubular detail parts. Occasional part rejection also occurs as a result of cutter slippage during the metal removal operations. The conventional approach to the problem of excessive weld underbead size is containment of the underbead by a metalic expandable, internal tooling. However, this approach is very expensive due to the high cost of each individual tool and the large inventory of tooling required to accommodate the multiplicity of girth weld diameters and weldment configurations. The metallic internal tooling approach is frequently design restricted since each tool will only accommodate a narrow range of girth diameters and tolerances, mechanical actuation and tooling installation and removal may be difficult or impossible, and noncircular joints substantially increase tooling complexity and fabrication costs.
It was found that the underbead may be controlled with a nonmetallic containment device.